[Lustre-devel] [RFC] "lctl readonly" modification proposal

[Alex Zhuravlev]

my 2c:

__lvfs_set_rdonly() -> fsync_bdev() -> fsync_super() -> ext3_sync_fs():

if (journal_start_commit(EXT3_SB(sb)->s_journal, &target)) {
if (wait)
  log_wait_commit(EXT3_SB(sb)->s_journal, target);

if this is called by process started transaction - deadlock before rdonly
if some another process holding transaction hits assertion - again deadlock before rdonly.

thanks, Alex


> On Thu, 21 Aug 2008 13:24:08 +0400, Alexander Zarochentsev  
> <Alexander.Zarochentsev at sun.com> wrote:
> 
> > On 20 August 2008 23:42:39 Mikhail Pershin wrote:
> >> Also to be sure that all before barrier is on disk, many test cases
> >> about recovery rely on the fact that operations before barrier are 
> on
> >> disk. This is important with HARD failure case especially, without
> >> sync before barrier the operations before barrier may be lost and
> >> affect the tests. I agree that syncless variant of barrier is needed
> >> but we also need barrier with sync depending on test case.
> >
> > You don't need lctl readonly to do a sync, the replay_barrier function
> > from test-framework.sh adds a sync explicitly
> 
> You are right, it is safe in that case.
> 
> 
> -- 
> Mikhail Pershin
> Staff Engineer
> Lustre Group
> Sun Microsystems, Inc.
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